Brake disk

Abstract

A brake disk according to the present invention incorporates a large number of air ducts defined in a disk portion having opposite sides to be clamped between friction pads, with the air ducts extending radially through the disk portion, and a plurality of joining portions formed on a mounting flange portion at circumferential distances and joined to a wheel hub by bolts. The disk portion is formed so that the heat capacity thereof is larger in an area nearer to the joining portions and smaller in an area more remote from the joining portions. The distance between adjacent ones of a large number of partitions defining the air ducts can be smaller in a location nearer to the joining portions and larger in a location more remote from the joining portions. Alternatively, a large number of partitions defining the air ducts are formed so that the ones nearer to the joining portions are larger in wall thickness and the partitions more remote from the joining portions are smaller in wall thickness.

What is claimed is: 
     
       1. A brake disk comprising: a plurality of air ducts defined in a disk portion having opposite sides to be clamped between friction pads, said plurality of air ducts extending radially through the disk portion; and a plurality of joining portions formed on a mounting flange portion at circumferential distances and joined to a wheel hub by bolts, wherein said disk portion air ducts are spaced circumferentially around said disk portion to provide less air passage and greater heat capacity in areas of said disk portion nearer to said joining potions and greater air passage and less heat capacity in areas of said disk portion more remote from the joining portions.   
     
     
       2. A brake disk according to claim 1, wherein a distance between adjacent ones of a plurality of partitions defining the air ducts is smaller in a location nearer to the joining portions and larger in a location more remote from the joining portions. 
     
     
       3. A brake disk according to claim 1, wherein a plurality of partitions defining the air ducts are formed such that said plurality of partitions nearer to the joining portions are larger in wall thickness, and said plurality of partitions more remote from the joining portions are smaller in wall thickness. 
     
     
       4. A brake disk comprising: a disk portion having opposite sides clamped between friction pads;   a plurality of air ducts defined between the opposite sides of said disk portion and radially extending through said disk portion, said plurality of air ducts being defined by a plurality of partitions;   a mounting flange portion connected to an inner periphery of said disk portion; and   a plurality of joining portions formed on said mounting flange portion at circumferentially spaced apart distances, the brake disk being mounted to a wheel hub through said plurality of joining portions by bolts, wherein   said disk portion has first and second areas, the first areas being located nearer to said plurality of joining portions than said second areas, and   the plurality of partitions defining said radially extending air ducts in said first areas of said disk portion are arranged to provide less air flow and greater heat capacity than the arrangement of the plurality of partitions defining said radially extending air ducts in said second areas.   
     
     
       5. A brake disk according to claim 4, wherein a distance between adjacent ones of the plurality of partitions defining the air ducts in the first areas is smaller than a distance between adjacent ones of the plurality of partitions in the second areas. 
     
     
       6. A brake disk according to claim 4, wherein adjacent ones of the plurality of partitions in the first areas are larger in wall thickness than adjacent ones of the plurality of partitions in the second areas.